This is an ongoing prospective study to determine the efficiency of hearing conservation in patients with endolymphatic hydrops (Meniere's disease) following endolymphatic sac decompression and drainage surgery. In addition, subjective and objective data about all patients screened is placed on computer for multi-variable statistical analysis. The value of the provocative glycerol test, as a diagnostic tool for endolymphatic hydrops, is being evaluated with very promising results. Biopsies of the endolymphatic sac epithelium are being studied at the ultrastructural level to determine the pathogenesis of the inner ear fluid imbalance.